Abstract: On September 11, 2003, Employee #1, a foreman for L & J Framing in Santee, CA, and six coworkers were framing a single story commercial building in a large strip mall. A day or two earlier, 4 ft long by 6 ft wide roof openings had been cut by the contractor for HVAC units. The openings were covered by plywood that was secured in place and marked with the appropriate hazard warnings On the day of the accident, Employee #1 pried open one of the plywood covers to install metal flashing around it to support the HVAC unit. He then picked up the cover and was walking forward when he fell approximately 20 ft through the opening, landing on the concrete pad in the store. Employee #1 was transported to Sharp Hospital, where he died. The covers had been secured and were marked with hazard warnings.